This invention relates to a device, system and method for organizing, managing and storing optical fibers during and after the production of an optical or opto-electronic assembly.
The advantages of combining optical signal processing with electrical applications are known, particularly in the telecommunications industry. Conventional manufacturing techniques for producing opto-electronic assemblies typically entail mounting electrical components onto the surface of a substrate, typically a printed circuit board, and establishing mechanical and electrical connections between the electrical components and the circuit board using solder joints. Opto-electronic components may be electrically and/or mechanically mounted to the printed circuit board in similar fashion. In addition, the optical fibers connected to and extending from the individual opto-electronic components must be linked in order to complete the optical signal paths in order to perform the desired function of the final assembly. Known methods such as fusion splicing or ribbon splicing accomplish this task.
Conventional optical and opto-electronic production practices are subject to various constraints. First, optical fiber is sensitive to excessive bending which places constraints on the layout or design of the circuit board assembly. Components need to be mounted onto the printed circuit board surface so that the curvature radius of the optical fiber extending between the components is not less than a minimum bend radius of the fiber. Bending an optical fiber below the minimum bend radius degrades optical signal strength and introduces transfer errors. In addition, optical fiber generally should not be routed near components having sharp edges or components emitting heat as these features can have deleterious affects on the optical fiber. These constraints on the use of optical fiber tend to produce printed circuit boards cramped and crowded with opto-electronic and electronic components.
Second, managing and organizing optical fiber during the assembly process can be a difficult endeavor. As advances in technology continue to expand the applications and capabilities of opto-electronics, the demand for more complex devices having ever-increasing numbers of opto-electronic components and fibers shows no sign of diminishing. In addition, each opto-electronic component oftentimes requires multiple optical fiber connections. This leads to opto-electronic assemblies with many optical fibers which creates highly congested fiber pathways across the substrate surface during the assembly process.
Compounding this fiber congestion is the excess length each optical fiber requires for splices and re-splices. Organizing the fibers, keeping track of the origin of the optical fibers, ensuring the proper fibers are being connected, while simultaneously maintaining the functional integrity of each optical fiber can be a daunting task for even the most experienced assembler. This makes for an assembly process that is highly detail-oriented, extremely time consuming, labor intensive and very inefficient. Moreover, increasing the number of optical connections compounds defect rates which prompts more frequent service and repair to the fibers and components. In addition, conventional fusion splice and optical component yields (i.e., the number of functional optical connections prepared per the number of attempted fusion splices) can range anywhere between 60% to 90%, further compounding the problem.
Furthermore, known devices and methods of storing excess fiber in a loop (i.e., excess optical fiber resulting from the fusion splicing process) typically wrap the fiber through or around a guideway or similar structure. This requires the length of the post-spliced fiber to be a whole increment of the guideway perimeter so as to avoid fiber slack when stored. The same drawback applies to the re-splicing process. Only re-splice fiber lengths in multiples or increments of the guideway perimeter can be used so that the length of the fiber after the re-splice will properly fit into the storage guideway without any slack. Thus, if a re-splice requires only one-half the length of the guideway perimeter, the remaining half length of fiber must be discarded so that the post-splice fiber length fits properly into the storage device.
A need therefore exists for a system, device and method which can organize and manage optical fiber during the production of optical and opto-electronic assemblies. A need further exists for a more efficient, versatile and less wasteful manner of storing excess optical fiber attached to optical and opto-electronic assembly.
In accordance with the present invention, an improved optical fiber management system for organizing and managing optical fibers for an optical assembly is provided. The system includes an optical assembly having an arrangement of a plurality of optical components. The optical components are arranged to define a space between the components, the space defining an optical pathway. The system further includes an optical fiber, a tray and a ramp extending between the pathway and the tray. The optical fiber is extended between the pathway along the ramp and onto the tray so the radius of curvature for the fiber in the pathway, ramp and tray is greater than or equal to the minimum bend radius of the fiber.
In one aspect of the present invention, the system includes a substrate located at a first level having opto-electronic components arranged to define a space between the components. The space defines a pathway on the substrate for the optical fibers. The optical fibers are formed into a fiber bundle and routed through the space. The pathway can be aligned with a ramp which carries the fiber bundle from the substrate to a storage tray located at a second level. The pathway and ramp route the fiber bundle so that the curvature radius of the optical fibers is greater than or equal to the minimum bend radius of the fiber. Similarly, the system stores loops of excess optical fiber at or above the minimum bend radius.
In one aspect, the optical fiber management system of the present invention, the opto-electrical components defining the space have a height, such as a height above the substrate when mounted thereto, which exceeds the height over which the optical fiber bundle can pass. A plurality of fiber bundles are routed through a plurality of pathways and the fiber bundles are extended away from the substrate. Individual optical fiber connections are formed between fibers from the same fiber bundle or from fibers from different fiber bundles. These connections provide optical pathways between the opto-electrical components. The system also includes connecting fiber bundles to other fiber bundles to form optical pathways.
In accordance with another aspect of the present invention, a device for routing optical fiber from one level to another level is provided. The device includes an arrangement of opto-electronic components on a substrate located at a first level, a storage tray located at a different or a second level, and a ramp extending between the substrate and the tray. Optical fibers formed into a fiber bundle are routed from the substrate along the ramp and into the tray. In one embodiment, the ramp includes channels which support the fiber bundles as they travel to the tray so that the radius of curvature for the optical fibers is greater than or equal to the minimum bend radius. The channels may merge into passages which carry and support a plurality of fiber bundles to the tray.
In accordance with another aspect of the present invention, an optical fiber storage device is provided. The storage device includes a tray, a storage area, an optical fiber inlet and outlet and a guide for preventing the optical fiber stored in the tray from having a radius of curvature less than the minimum bend radius. The optical fiber is stored as a loop in the tray. The loop is larger than the minimum size loop that is defined by the guide, the loop being unconstrained or substantially unconstrained. The size of the storage area relative to the guide enables the optical fiber loops larger than the guide to reside in the tray unconstrained. The tray has no guideway defining an upper boundary for the fibers. This allows the tray to store optical fibers over a very wide range of lengths with the minimum length defined by the guide which also determines the minimum radius of curvature of a loop stored therein. Lips extending around the perimeter of the tray retain the optical fiber loops in the tray. In one embodiment, the guide may be teardrop-shaped or curved. The guide may also be formed by an array of spaced-apart upright members which define a radius of curvature that is greater than or equal to the minimum bend radius.
In accordance with another aspect of the present invention, a device for storing optical fiber which has heat dissipating structure is provided. The device includes an optical fiber storage tray having a base and an optical fiber inlet and outlet. The base has one or more and preferably a plurality of perforations through which heat can freely pass. When the tray is positioned above or below the substrate, the perforations allow heat generated from the opto-electronic components to freely pass therethrough. The tray may further include an optical fiber guide to define a minimum bend radius wherein the guide may be perforated. In one embodiment, a fin may extend along the underside of the perforated base and direct a flow of heated air from or cool air to the components.
In another aspect of the invention, the fiber management system provides for an optical fiber storage tray having a fin extending along the underside of the tray. The fin is shaped to direct heated air generated by the components away from heat-generating components or from the substrate. The tray may be made of a conductive material and absorb radiant heat away from the components.
In accordance with still another aspect of the present invention, a method of assembling an opto-electronic assembly is provided. In accordance with this method, the optical fibers are formed into a bundle having an intermediate length. Opto-electronic components having a height exceeding the height over which the optical fiber bundle can pass are arranged on a substrate so as to define a space between the components. The space comprises a pathway for the bundle. The pathway is formed so that any curvature of the pathway has a radius of curvature that is greater than or equal to the minimum bend radius of the fiber in the bundle.
At least a portion of the intermediate length is routed through a portion of the pathway. The method may further include routing a plurality of fiber bundles away from the substrate through a plurality of pathways. Optical fiber pathways are formed by connecting individual optical fibers to other optical fibers or by connecting fiber bundles to other fiber bundles. These optical connections produce optical pathways.
In accordance with another aspect of the present invention, a method of storing excess length of optical fiber extending between optical components located on a substrate is provided. In accordance with this method, a tray is provided having an optical fiber inlet opening and a storage area. Optical fibers are passed through the optical fiber inlet and into the storage area and form an unconstrained unbundled loop with each of the optical fibers on the tray. The unbundled loops each have a radius of curvature greater than or equal to the minimum bend radius of the optical fiber. The method further includes extending the optical fibers between the substrate and the tray by routing the optical fibers on a ramp. Typically, the optical fiber on the tray will be exited via an optical fiber outlet that can be the same or different opening from the inlet opening.